1. Field of the Invention
The present invention is directed to a free-piston regenerative hydraulic engine having a displacer piston, an inertial mass and a hydraulic output.
2. Prior Art
A number of free-piston Stirling engines have been proposed which utilize a free displacer piston actuated by a gas reservoir pressure or "bounce pressure" acting on a small differential area of the piston. For example, the Dehne patent, U.S. Pat. No. 3,530,681, disclosed a cryogenic refrigerator expander and compressor pistons which are actuated under the influence of refrigerant pressure and hydraulic pressure. The hydraulic pressure entering the drive unit 28 through the hydraulic pumps P1 and P2 acts on the small differential area of the piston rods 15 and 16. The Dehne patent does not disclose a displacer piston, a working piston and a diaphragm as set forth in the present invention.
In addition, a number of prior art Stirling engines have been proposed which include a displacer piston interconnected with a working piston by means of a piston rod. The Kress patent, U.S. Pat. No. 3,630,019, the Gothberg patent, U.S. Pat. No. 3,782,119, the Gartner patent, U.S. Pat. No. 3,889,465, and the Abrahams patent, U.S. Pat. No. 3,886,743, disclose pressure operated engines which include a displacer piston connected to a working piston by means of a piston rod. None of the patents listed above disclose a free displacer piston acting through a free inertial mass in combination with a diaphragm member as proposed in the present invention.
Further, developments have been proposed in the prior art to control the operation of a Stirling engine. The Jaspers patent, U.S. Pat. No. 3,886,744, and the Bergman patent U.S. Pat. No. 3,902,321, disclose a power regulating system in combination with a Stirling engine. However, the Jaspers patent and the Bergman patent do not disclose a free displacer piston and a free inertial piston in combination with a diaphragm as set foth in the present invention.